BAGHDAD, Iraq -- A Blackwater USA contractor's killing of an Iraqi security guard is putting new pressure on the Bush administration to prosecute private-company employees accused of crimes in Iraq, and highlighting the murky legal status of the 130,000 foreign contractors working there.

The Christmas Eve shooting is one of the few known cases of an American contractor killing an employee of the Iraqi government, and it remains one of the rare lethal shootings inside Baghdad's fortified Green Zone. Criminal charges in the case, which is being investigated by the Federal Bureau of Investigation and the Justice Department, would be unprecedented. To date, no U.S. contractor has been put on trial for murdering an Iraqi.

The incident began when an off-duty Blackwater employee who had been drinking heavily tried to make his way into the "Little Venice" section of the Green Zone, which houses many senior members of the Iraqi government, according to U.S. and Iraqi officials. He was stopped by Iraqi bodyguards for Adil Abdul-Mahdi, the country's Shiite vice president, and shot one of the Iraqis, according to U.S. and Iraqi officials. The bodyguard died at the scene, the officials say. The contractor was fired by Blackwater and has returned to the U.S. The company has declined to disclose his name.

The investigation is a setback for Blackwater, one of the best known -- and most profitable -- of the army of security companies operating in Iraq and Afghanistan. Blackwater has flourished by capitalizing on the Bush administration's push to outsource key aspects of the war, like escorting supply convoys and protecting U.S. bases and senior officials. The closely held company, founded in 1997 by former Navy SEALS, holds government contracts valued at about $800 million a year, according to people familiar with the matter.

Only two contractors out of the tens of thousands who have been deployed to Iraq and Afghanistan over the past 5〓 years have been indicted for violence, and only one has been convicted. Given the aggressive tactics contractors use in both countries, where they routinely force vehicles off the road or shoot at cars that draw too close to them, Democrats and Iraqi officials say there should be more indictments and convictions.

"This is one of the biggest grey areas of the entire war effort," said Rep. Jan Schakowsky (D., Ill.), the sponsor of legislation requiring the Bush administration to collect and publicize detailed data about contractors. "There are almost as many contractors in Iraq as soldiers, and they seem to be entirely outside the reach of the law."

Jaclyn Lesch, a spokeswoman for the Justice Department, said the agency has "no reluctance to pursue such cases where there is evidence supporting a charge and jurisdiction to prosecute." She declined to comment on whether charges were coming in the Blackwater employee's shooting of the bodyguard, Raheem Khalaf al-Saraay.

Blackwater spokeswoman Anne Tyrrell said the "appropriate authorities, including the United States Department of Justice, are investigating the incident," and that the company was "cooperating fully with the inquiry."

The company has reason to tread carefully. Aides to Mr. Abdul-Mahdi say relatives of the victim are nearly certain to file a civil lawsuit in the U.S. against Blackwater, which is already embroiled in a pair of high-profile suits. In the first case, relatives of three U.S. soldiers killed in a crash of a Blackwater airplane in Afghanistan are suing a Blackwater affiliate for negligence in a Florida court. In the second, relatives of four Blackwater security guards killed in Fallujah, Iraq, are suing the company for wrongful death in a state court in North Carolina. Blackwater and its parent company, Prince Group LLC, have denied wrongdoing and are fighting both suits.

The Afghanistan lawsuit is being closely watched in legal circles because its outcome could help determine the extent of contractor liability in civil cases arising from their government work. The criminal investigation into the Green Zone shooting is also largely uncharted territory, since it remains unclear what -- if any -- law applies to the American contractors operating in Iraq. Congress last year passed legislation allowing contractors to be tried under the military's Uniform Code of Military Justice. But no American contractors have faced such charges, and U.S. officials concede it is unclear whether it would even be legal to use military law to try civilians.

The only contractor convicted of assault for work in Afghanistan or Iraq is David Passaro, a contractor for the Central Intelligence Agency who was found guilty last August of beating an Afghan detainee who later died of his wounds. Mr. Passaro was convicted under a little-used provision of the Patriot Act, rather than under the Military Extraterritorial Jurisdiction Act, passed by Congress in 2000 specifically to combat contractor misdeeds.

The Bush administration has been reluctant to use MEJA. No contractor was indicted under the law until March 1, when former Kellogg Brown & Root employee Aaron Langston was accused of stabbing an Indian colleague in the throat with a knife. His trial has yet to begin.

The current investigation of the Green Zone incident could pose problems for Blackwater. Best known for protecting dignitaries like former American proconsul Paul Bremer and current U.S. Ambassador Ryan Crocker, Blackwater has hundreds of employees in Iraq and maintains its own helicopters, airplanes and armored vehicles there.

The company was created in 1997 by Erik Prince, a Michigan native and former Navy SEAL whose father was a wealthy auto-parts supplier. Mr. Prince is a political conservative who has donated more than $100,000 to Republican candidates and campaigns since the mid-1990s, according to the Center for Responsive Politics.
In Iraq, Blackwater's security personnel are widely considered to be among the best, though most aggressive, of the contractors in the country. At least 23 of its employees have been killed in Iraq, but the company boasts that it has never lost any of the people it was hired to protect.

The Blackwater employee suspected in the December killing was a technician hired to maintain and repair Blackwater's weaponry and armaments, according to people familiar with the matter.

Current and former colleagues of the contractor say he had been drinking heavily in the hours before his fatal run-in with Mr. al-Saraay, and that FBI agents probing the shooting ran blood tests to see if he was legally drunk at the time of the shooting. The results of those blood tests are unknown, and the FBI declined to comment.

The Iraqi officials say that representatives of Blackwater visited with Mr. al-Saraay's family to apologize for the shooting and offer them up to $100,000. Relatives of the security guard, who had young children, accepted the money but made clear they wanted to see the contractor jailed, the Iraqi officials say. Ms. Tyrrell, Blackwater's spokeswoman, denied the company had offered $100,000 in reparations but declined to comment further, saying that discussing any potential Blackwater offer to the family could "endanger lives in Iraq."